Corneal implant and method of delivering a corneal implant

ABSTRACT

A method of inserting and securing a corneal implant in engaging and fluid-flow limiting relation to the posterior cornea, such as to treat edema. The method includes securing a corneal implant in fluid flow limiting relation to the posterior cornea through an incision in the eye and securing it in place by a variety of steps such as corneal insertion or laser bonding, and preferably by inserting a removable corneal implant including a central region and a plurality of retention member(s) disposed on the periphery thereof into the eye so as to releaseably and removably engage a portion of the eye and thereby retain the corneal implant in abutting and engaging relation with the posterior cornea. The retention members of the corneal implant may also comprise haptic leg(s) extending from the central region and having a biasing configuration structured to be disposed in contacting relation with the iris and/or iridocorneal angle in biasing relation of the central region against the posterior cornea.

CLAIM OF PRIORITY

The present application is based on and a claim of priority is made topreviously filed, co-pending U.S. provisional patent application havingSer. No. 61/550,087 filed on Oct. 21, 2011 with the United States Patentand Trademark Office, which is incorporated herein by reference in itsentirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to corneal implants and to a method ofdelivering and securing corneal implants in fluid-flow limiting relationto the posterior cornea, such as to treat corneal edema, includingremovably securing the corneal implant.

2. Description of the Related Art

Excess corneal fluid, also known as corneal edema, is a painfulcondition caused by an accumulation of fluid within the cornea that canlead to loss of corneal clarity and visual acuity. Corneal edema is mostoften the result of a decreased number or decreased function of thecorneal endothelial cells that form a monolayer lining the inside, orposterior, side of the cornea. For example, the endothelial cells canfail to adequately pump aqueous fluid that diffuses into the cornea fromthe anterior chamber out of the cornea and back into the anteriorchamber.

Current treatment for corneal edema includes medical treatment andtherapy to dehydrate the cornea with hypertonic saline, and in somecases, corneal transplant. There are approximately 50,000 cornealtransplants performed each year in the United States, with similarstatistics for Europe. The three major indications for cornealtransplant are Fuchs' dystrophy, pseudophakic bullous edema, and cornealtransplant rejection. Corneal transplants in the United States andabroad are limited, however, by tissue accessibility, surgical cost,long patient recovery time, changes in refraction affecting vision,availability of corneal specialists, and the risk of transplantrejection or failure, which can be in the range of 10-30%.

Corneal implants have been developed to treat edema while attempting toavoid some of the problems of transplant surgery. For instance,synthetic corneal implants can be used in place of tissue, therebyobviating issues of tissue availability and limiting the possibility ofhost rejection. However, there are still no acceptable ways of insertingand securing the corneal implants to the eye of a patient that willminimize interference with visual acuity and damage to the eye. Forexample, some known methods involve suturing the implant to the cornea,or applying a bonding agent to permanently bond the implant to thecornea. However, suturing the implant creates scar tissue, which caninterfere with vision, and may be rejected by the patient's body.Bonding agents may cause chemical damage to the cornea or implant overtime, and also may affect vision. Moreover, known corneal implants andmethods only permit permanent attachment of the corneal implant, and mayeven preclude future corneal transplants.

Accordingly, it would be beneficial to have a method of inserting andsecuring a corneal implant to the cornea that does not interfere withvision, and possibly could even correct vision simultaneously withtreating corneal edema. In addition, it would also be beneficial to havea method of inserting a corneal implant such that it can later beremoved if necessary, such as for a replacement or if the patient'scondition subsides.

SUMMARY OF THE INVENTION

The present invention is directed to a method of delivering and maintaina corneal implant in proximity to the posterior cornea of a patient, aswell as to a preferred removable corneal implant. The method and cornealimplant are directed to protecting the cornea from excess fluid, such asfrom the anterior chamber of the eye, thereby keeping the corneadehydrated. In this manner, the present invention can be used to treatcorneal edema, or excess corneal fluid. Further, the method achievesremovable retention of the corneal implant in abutting engagement withthe posterior cornea such that the corneal implant can be removed at alater time if necessary. This is a significant advance over existingcorneal implant and transplant methods which permanently secure thecorneal implant to the eye and do not allow the implant to be removed,and in some cases even preclude future corneal transplants. Moreover,the corneal implant of the present invention may be configured tocorrect vision upon implantation, including myopia, hyperopia, andbifocal correction, in addition to treating corneal edema.

More in particular, in a first preferred embodiment of the presentmethod, a corneal implant including one or more retention members isutilized, the retention members engaging portions of the eye toremovably secure the corneal implant in a fluid flow limiting positionrelative to the posterior cornea. Particularly, the method can comprisean initial step of creating an incision in the eye of a patient needingthe corneal implant, such as in proximity to the cornea, and theninserting through the incision a corneal implant having a central regionand at least one retention member extending from the periphery of thecentral region. To facilitate entry, the corneal implant may betemporarily compressed or folded for insertion through an incision of asmaller dimension than the diameter of the corneal implant, although itis understood that a sufficiently large incision can be made toaccommodate an unfolded corneal implant. Once inserted, the cornealimplant is positioned in engaging and fluid-flow limiting relation tothe posterior cornea and secured in place by engaging a portion of theeye with the retention members. Because the retention members can laterbe removed from that engagement, the retention members are able toremovably retain the corneal implant against posterior cornea.

For example, in one embodiment the retention member(s) comprise a hookor claw-type configuration which may be pressed into the posteriorcornea to secure the corneal implant in position. Furthermore, theretention member(s) may comprise at least one haptic leg secured to andextending from the central region of the corneal implant, such that whenpositioned, the distal end of the haptic leg(s) contacts the iris and/oriridocorneal angle and biases the central region of the corneal implantagainst the posterior cornea, thus maintaining an optimal close, fluidflow limiting contact.

In another embodiment, the method of inserting a corneal implantincludes inserting the implant, with or without retention members, intothe corneal stroma in or near the posterior cornea. Specifically, themethod comprises creating an incision in the eye, such as in the corneaor near to the cornea, and inserting the implant through the incisionand into the corneal stroma in fluid-flow limiting relation to theposterior cornea, such as anterior to the Descemet's membrane. In somecases this method may further involve excising a portion of the eye inproximity to the posterior cornea from the corneal stromal side, such asfrom the sclera or directly in the cornea, thereby creating a cornealpocket. For example, this may entail excising a portion of deep cornea,creating a deep laminectomy corneal pocket. This pocket is then extendedinto the corneal stroma, preferably the posterior corneal stroma justanterior to Descemet's membrane, forming a deep corneal pocket. Onceformed, the corneal implant is inserted through the incision, throughthe pocket, and positioned within the corneal pocket in engaging andfluid-flow limiting relation to the posterior cornea, such as adjacentand anterior to the Descemet's membrane. The incision is then closedleaving the corneal implant in its proper location.

In still another possible embodiment of the present method, a laser isused to bond the corneal implant in position relative to the posteriorcornea. Specifically, the method in this embodiment comprises creatingthe incision in the eye of the patient needing the corneal implant,again preferably in proximity to the cornea. A corneal implant is theninserted through the incision and positioned in engaging, fluid-flowlimiting relation to the posterior cornea. With the implant positioned,a laser is applied at a plurality of locations along the perimeter ofthe corneal implant, and may be applied continuously along the perimeterand/or along substantially the entire perimeter of the corneal implant.The laser application is maintained until the corneal implant is bondedwith the posterior cornea. It is understood that if desired a cornealimplant with one or more retention members may also be used.

In addition to the aforementioned method, the present invention is alsodirected to an improved corneal implant, preferably, but not necessarilyconfigured for use with one of the preceding methods. In this regard,the corneal implant can preferably include a central region made of abiocompatible polymer material, such as a hydrophobic material, which istransparent to allow for visibility therethrough. The central regionalso preferably has an index of refraction high enough to permitrefractive vision correction if needed. Preferably, the central regionof the implant has an arcuate configuration that corresponds with andmatches the curvature of the posterior cornea. This shape promoteseffective placement of the corneal implant in abutting engagement withthe posterior cornea upon implantation in a manner that resists fluidflow.

The corneal implant further includes at least one, but preferably aplurality of retention members secured to and extending away from aperiphery of the central region. These retention members, which can beintegral with the central region, each have a contact point disposeddistally from the central region of the implant and in contactingrelation with the eye upon implantation. Preferably, these contactpoints removably engage the eye in a manner that urges and retains thecentral region of the corneal implant in position relative to theposterior cornea. To achieve effective positioning, the retentionmembers can include clasps, hooks, or other similar structures that arestructured to engage a portion of the eye, such as the posterior corneaor other nearby ocular structure, to secure the corneal implant inposition while permitting later disengagement of the eye and removal ifnecessary.

In some embodiments, the retention members comprise at least one, butideally two to four haptic legs each having a contact point disposeddistally from the central region to engage a portion of the iris and/oriridocorneal angle. The haptic leg(s) further have a biasingconfiguration which may be hinged to bias the central region of thecorneal implant against the posterior cornea, such as by applyingpressure to the central region upon implantation, when they are inposition to effectively push off against the portion of the eye to whichthey are engaged. Moreover, the corneal implant may include only hapticleg(s), only other types of retention member(s), or any combinationthereof.

These and other objects, features and advantages of the presentinvention will become clearer when the drawings as well as the detaileddescription are taken into consideration.

BRIEF DESCRIPTION OF THE DRAWINGS

For a fuller understanding of the nature of the present invention,reference should be had to the following detailed description taken inconnection with the accompanying drawings in which:

FIG. 1 is a planar view of the posterior side of the corneal implant ofthe present invention.

FIG. 2A is a side view of one embodiment of the corneal implant of FIG.1.

FIG. 2B is a side view of another embodiment of the corneal implant ofFIG. 1.

FIG. 3 is a side view of the corneal implant of FIG. 1 upon implantationand in position relative to the eye, shown in cross-section.

FIG. 4 is a planar view of the posterior side of another embodiment ofthe corneal implant of the present invention including haptic legs.

FIG. 5 is a side view of one embodiment of the corneal implant of FIG.4.

FIG. 6 is a side view of the corneal implant of FIG. 4 upon implantationand in one position relative to the eye, shown in cross-section, whereinthe haptic legs contact the iris.

FIG. 7 is a side view of the corneal implant of FIG. 4 upon implantationand in another position relative to the eye, shown in cross-section,wherein the haptic legs contact the iridocorneal angle.

FIG. 8 is a schematic diagram of one embodiment of the present methodwhereby the corneal implant is secured by at least one retention member.

FIG. 9 is a schematic diagram of one embodiment of the present methodwhereby the corneal implant is secured in a corneal pocket.

FIG. 10 is a side view of the corneal implant upon corneal insertion bythe method of FIG. 9, shown in cross-section.

FIG. 11 is a close-up side view in cross-section of the placement of thecorneal insert in relation to the layers of the cornea.

FIG. 12 is a schematic diagram of one embodiment of the present methodwhereby the corneal implant is secured by laser.

Like reference numerals refer to like parts throughout the several viewsof the drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention is directed to a method of delivering and securinga corneal implant to the posterior cornea of a patient, preferably in aremovable manner, as well as to a corneal implant that can preferably beimplemented with that method. The method can be used to insert cornealtransplants, such as from a live or recently deceased donor, althoughpreferably, and as will be described in greater detail, it is preferablyused for the introduction of corneal implants made of natural orsynthetic material. It is noted that for purposes of clarity thesubsequent description of the present method may be described using thepreferred corneal implant, however, such use of the preferred cornealimplant in said description is not intended to be limiting or tonecessarily require use of the preferred corneal implant. More inparticular, this preferred corneal implant can be made of amedical-grade biocompatible material, such as a polymer, which isbiologically inert so as not to interfere with the patient'sbiochemistry. For example, the corneal implants inserted by the presentmethod can be made of acrylic polymers and its co-polymers, styrenepolymers and its co-polymers, siloxane polymers, including siliconerubber and its co-polymers, natural and synthetic collagen and itsco-polymers, fluoroethylene and its co-polymers. Moreover, the cornealimplant may have a sufficiently high refractive index to permit visioncorrection of the recipient upon implantation. Accordingly, the presentmethod can be utilized to treat corneal edema and other cornealdisorders, as well as to provide refractive correction, independent oftissue donors and the problems attendant to using living tissue, such aswaiting for an appropriate donor, matching the blood type, antigens, andother factors between the donor and recipient, screening for diseases inthe donor tissue, possible host rejection, post-operative infections,etc.

As previously noted, the methods of inserting a corneal implant, to bedescribed, are preferably, but not necessarily, achieved using thepreferred embodiment of the corneal implant with certain optimalcharacteristics and structure. Before discussing the specificembodiments of the present method, however, the preferred cornealimplant 20 is described. Specifically, this preferred corneal implant20, includes a central region 22 which is preferably generally round,and is at least partially transparent so as not to interfere with thevision of the patient. Further, the central region 22 preferablymeasures approximately 3-10 millimeters in diameter, although it mayoptimally be 5-6 millimeters in diameter in certain embodiments. Atleast the central region 22 is preferably made of a biocompatiblepolymer material, such as described previously, which is biologicallyinert and of medical grade quality. For example, the central region 22,can be formed of hydrophobic materials such as acrylic, poly(methylmethacrylate) (PMMA), poly(styrene-block-isobutylene-block-styrene)(SIBS), silicone rubber such as polydimethylsiloxane (PDMS),chlorotrifluoroethylene (CTFE). Alternately, however, it may be made ofa hydrophilic material, examples of which include poly(2-hydroxyethylmethacrylate-co-methylmethacrylate) (pHEMA-MMA) and poly(2-hydroxyethylmethacrylate-co-ethylmethacrylate) (pHEMA-EMA), having a water contentin the range of about 10-50%, or natural or synthetic collagen.Accordingly, the central region 22 is structured and positioned toinhibit the flow of excess corneal fluid when oriented pursuant to thepresent method.

Furthermore, many of these materials are at least semi-rigid, and assuch it may be preferred that the hardness or stiffness of the centralregion 22 be approximately equivalent to the rigidity of the cornea. Forinstance, the hardness or stiffness of the central region 22 may beapproximately 10 MPa, although greater degrees of rigidity arecontemplated. Conversely, however, these same materials are also stillsomewhat flexible, thus making the central region 22 at leasttemporarily foldable so as to reduce a dimension thereof forimplantation of the corneal implant 20 in the described method.

It is also noted that the central region 22 is configured to correspondto the contour of the posterior cornea. As seen in FIGS. 1-3, thecentral region 22 has an arcuate, or curved, configuration providing ananterior surface 26 disposable toward the front of the eye onimplantation, and a posterior surface 27 disposable in facing relationto the interior of the eye upon implantation. The anterior surface orcurvature 26 is structured to correspondingly match a curvature of theposterior cornea, as seen in FIG. 3, which shows the corneal implant 20in position relative to the cornea 10 and remaining portions of the eyeupon implantation, including the anterior 11 and posterior 12 portionsof the cornea 10, as well as the anterior chamber 13, iris 14, lens 15,vitreous humour 16, conjunctiva 17, and sclera 18.

While the anterior 26 and posterior 27 curvatures of the central region22 may be collectively disposed to provide a net optically neutraltransmission of light, that is, no vision correction, in someembodiments the central region 22 may comprise a vision correctingconfiguration, wherein the index of refraction of the central region 22is sufficiently high to permit correction of refraction uponimplantation. For instance, the central region 22 may be configured sothat the anterior 26 and posterior curvatures 27 collectively createdioptric correction of a patient's vision, such as myopia or hyperopia,or even multifocal correction allowing for near and far vision, uponimplantation of the corneal implant 20. Accordingly, the corneal implant20 may comprise varying widths to accomplish the various types of visioncorrection. By way of example, the central region 22 may be thicker inthe center than at the edges, or vice versa, and one edge could be of adifferent thickness than an opposite edge.

Looking further to FIGS. 1-3 and a preferred embodiment of the cornealimplant 20, it also preferably includes at least one retention member 24disposed along the periphery of the central region 22. The one, butpreferably more than one retention members 24 are secured to andextending away from the central region 22. In this regard, the retentionmembers may be integrally formed with the central region 22, such as ofthe same material, and/or may be separately formed and secured to thecentral region 22 as needed for proper fastening. Moreover, theretention member(s) 24 may be made of different material than thecentral region 22 of the corneal implant 20. For instance, the retentionmember(s) 24 may be made of a softer or more flexible material than thecentral region 22, or alternatively may be less flexible than thecentral region 22, and need not be transparent. Also, the retentionmember(s) 24 may comprise a hydrophilic material so as to be morecompatible with the tissue of the eye which they contact and/or engage.In the illustrated embodiment, each retention member 24 has a width ofapproximately 0.5-5 micrometers, although it is contemplated that thatwidth may vary, and indeed, in at least one embodiment, the retentionmembers can measure 1-2 micrometers wide.

Each retention member 24 is structured and disposed to removably retainthe corneal implant 20, and more in particular the central region 22thereof in position relative to the posterior cornea upon implantation,maintaining placement but nevertheless permitting removal of the cornealimplant 20, if necessary. For instance, as will be described in greaterdetail subsequently and as best seen in FIGS. 2A and 2B, the retentionmember(s) 24 may comprise a hook or claw type structure 28 or othersuitable structure that enables stable and yet removable retention ofthe corneal implant 20 in attached relation to the eye.

To facilitate engagement and securing of the corneal implant 20 to theeye, the retention member(s) 24 each preferably include a contact point25 disposed distally from the central region 22 of the corneal implant20, as seen in FIGS. 1, 2A, and 2B. The contact points 25 are disposedin contacting relation with an eye of the patient upon implantation, soas to retain the corneal implant 20 in abutting engagement relative tothe posterior cornea 12, and may act as the point of at least initialengagement for each retention member 24 upon securing to the posteriorcornea 12. For example, in at least one embodiment the retention members24 can be pressed into the posterior cornea 12 such that the contactpoint 25 is the piercing point which first enters the corneal stromaleading the way for at least partial implantation of a remainder of theretention member 24 into the eye.

Looking further to the preferred corneal implant 20, and as shown inFIGS. 4-7, in at least one embodiment the retention members 24 caninclude at least one, but preferably two to four haptic legs 28′disposed either instead of or in addition to the other configurations ofretention members 24, such as the hook or claw type configuration 28.Accordingly, some embodiments of the corneal implant 20 will have onlyhook or claw type retention member(s) 28, some embodiments only hapticleg(s) 28′, and some embodiments will include a combination of hook orclaw type retention member(s) 28 and haptic leg(s) 28′. With particularreference to FIGS. 4 and 5 wherein the haptic legs 28′ are included as aretention member 24 in addition to other types of retention members 28,the haptic leg(s) 28′ are secured to and extend away from the centralregion 22 of the corneal implant 20 such that a combined diameter of thecentral region 22 and haptic leg(s) 28′ may be in the range of about12-16 millimeters, and may preferably be in the range of about 13-14millimeters. Each haptic leg 28′ ends in a contact point 25 disposeddistally from the central region 22, similar to the other types ofretention member(s) 28. The haptic legs 28′, however, have a biasedconfiguration which is structured to bias, or push, the central region22 against the posterior cornea 12 upon implantation, as depicted inFIGS. 6 and 7. For example, the haptic legs 28′ are structured toprovide sufficient pressure on the central portion 22 to maintain theposition of the corneal implant 20 in engaging and abutting relation tothe posterior cornea 12. The pressure applied by the haptic legs 28′ andthe central region 22 against the posterior cornea 12 depends on theparticular configuration and disposition of the haptic leg 28′, thematerial from which it is made, the tension or potential energy createdby positioning the haptic leg 28′, as well as other factors, but isnevertheless greater than intraocular pressure. For example, the hapticleg(s) 28′ may apply anywhere from 15-35 mmHg of pressure on the centralregion 22, and consequently, the posterior cornea 12. In one preferredembodiment, the pressure applied by the haptic legs 28′ is in the rangeof about 22-26 mmHg. Accordingly, and as seen in the embodiments ofFIGS. 4-7, the biasing structure of the haptic legs 28′ may comprise acurved, almost spring-like shape in order to create sufficient pressureof the corneal implant 20 on the posterior cornea 12. In someembodiments the haptic leg(s) 28′ may be hinged to increase or decreasepressure applied to the central region 22.

As best shown in FIGS. 6 and 7, the haptic leg(s) 28′ may be structuredto span at least a portion of the anterior chamber 13 of the eye inorder to bias the corneal implant 20 off neighboring portions of theeye. For example, the haptic legs 28′ are structured and disposed sothat the contact points 25 thereof releaseably engage a portion of theiris 14, as in FIG. 6, or the iridocorneal angle 19, as in FIG. 7.Accordingly, the haptic legs 28′ push off of the iris 14 or iridocornealangle 19, respectively, by virtue of the biasing configuration, tocreate the pressure on the central region 22, and thereby the posteriorcornea 12, to maintain placement of the corneal implant 20. It shouldtherefore be appreciated that the haptic legs 28′ may comprise anymaterial of sufficient strength, flexibility and resilience to createsuch a biasing effect. For example, the haptic leg(s) 28′ may be made ofa material that is harder or softer, and may be more or less flexible orpliable, than that of the central region 22 in order to achieve aparticular desired pressure on the corneal implant 20 against theposterior cornea 12. The haptic leg(s) 28′ may also comprise ahydrophilic material so as to be more compatible with the tissue of theeye which they contact and/or engage.

Taking into account these described, preferred embodiments of thecorneal implant, and as noted, the present invention is also preferablydirected to a method of inserting a corneal implant 20 in a manner thatit is, in the preferred embodiments removably positioned relative to theposterior cornea, thereby allowing for removal and if neededinterchanging of the corneal implant.

While it is noted that the each of the to be described embodiments ofthe present method, including the second embodiment where in the cornealimplant is inserted into the corneal stroma, may also be removable, theremovability is preferably achieved as will be described in connectionwith the first embodiment of the present method illustrated in FIG. 8.

Specifically, as noted, the present invention is directed to a method ofinserting a corneal implant, which in the first preferred embodiment, asat 300, may optimally utilize the preferred corneal implant includingone or more retention members. Moreover, looking in detail to themethod, the initial steps will be described in connection with saidfirst preferred embodiment for ease of explanation, although it is notedthat many of the initial steps will apply to the other embodiments aswell. In particular, once the eye is prepared for the procedure, themethod, such as at 300, comprises an initial step of creating anincision in the eye in proximity to the cornea, as at 310. In manyembodiments, the incision is made in the cornea itself, although it isunderstood that the incision may be made in other parts of the eye, suchas the sclera, conjunctiva, etc. The incision is ideally of a relativesmall size to minimize damage and stress to the eye, such as in therange of about 1.8 to 3.0 millimeters. However, larger incisions of upto about 6 millimeters are contemplated. The incision permits access tothe interior of the eye, such as to the anterior chamber and posteriorsurface of the cornea, against which the corneal implant will attach orbe pressed. Alternately, however, the term incision also contemplates amuch broader cut, such as what may be desired to create a corneal flap.It is understood that this incision can be made by manual, mechanical,or laser-based means as needed for precision.

Once the incision is made, the method, as at 300, also comprisesinserting a corneal implant into the cornea through the incision, as at320. Any corneal implant can be used in the present method, such asdescribed above, including transplant tissue, although the preferredcorneal implant described subsequently is preferred. In particular, thepreferred corneal implant is preferably structured of a sufficientlythin dimension and resilient material to be foldable or at leasttemporarily compressible, such that inserting the corneal implant isachieved by compressing the corneal implant to a dimension smaller thanthe size of the incision, and then fitting the corneal implant throughthe smaller incision. Of course, it is understood that larger incisionsmay be needed, however, for inserting corneal implants that are morerigid and not foldable, or wherein a folding or compressing of theimplant may be adverse to its ultimate function, such larger incisionsand/or more rigid implants also contemplated by the present invention.

In the preferred embodiments, the corneal implant is inserted into theanterior chamber, posterior cornea, or other part of the eye whichaffords the corneal implant access to the posterior cornea, or at leastthe posterior surface of the cornea. As such, once the corneal implantis inserted through the incision, the method, such as at 300, furthercomprises positioning the corneal implant in engaging and fluid-flowlimiting relation to the posterior cornea, as at 330. Specifically, asnoted, the corneal implant is preferably made of a material that resistsand/or limits the flow of aqueous fluid therethrough, such as ahydrophobic material. In some preferred embodiments, the material caninclude, although is not limited to, poly(2-hydroxyethylmethacrylate-co-methylmethacrylate) (pHEMA-MMA) and poly(2-hydroxyethylmethacrylate-co-ethylmethacrylate) (pHEMA-EMA), and which has a watercontent in the range of about 10-50%. Accordingly, the corneal implant,when positioned in contacting and engaging relation with the posteriorcornea, effectively restricts the influx of fluid from the anteriorchamber of the eye into the cornea by way of the corneal endotheliumlocated along the posterior surface of the cornea, thereby reducingexcess accumulation of fluid within the cornea. Of course, the cornealimplant need not entirely prohibit all fluid flow, as complete blockageof fluid flow would, in fact, be detrimental to eye health since sometransfer of anterior fluid is needed to provide nutrients to the corneafrom the body. Instead, the corneal implant is structured and positionedso as limit the excessive influx of fluid from the anterior chamber intothe cornea that causes edema, thereby restricting unwanted and painfulfluid accumulation. Therefore, the corneal implant is positioned whereit can be most effective at limiting influx of anterior fluid, and ispreferably secured in place as will be described subsequently in amanner that while it presses against the posterior surface of thecornea, is preferably not completely secured thereto along the entirecontacting surface.

Specifically, and with reference to FIG. 8, the method, as at 300, cancomprise inserting a corneal implant having at least one, but preferablya plurality of retention members into the eye. In this regard, FIG. 3illustrates the proper positioning of the corneal implant 20, and inparticular the central region 22, relative to the cornea 10 and othercomponents of the eye in this and other embodiments of the presentmethod. As previously noted, the corneal implant 20 is structured andpositioned to limit the flow of anterior fluid into the cornea 10, suchas by the corneal endothelium at the posterior cornea 12. Accordingly,the corneal implant 20 is positioned so as to engage the posteriorcornea 12, such as by abutting or confronting relation thereto. As alsomentioned above, the anterior curvature 26 of the central region 22 ofthe corneal implant 20 is configured to correspond with the posteriorcornea 12 in order to facilitate and maximize abutting engagement withthe posterior cornea 12.

Once positioned, the method, as at 300, further comprises securing thecorneal implant in engaging and fluid-flow limiting relation to theposterior cornea by engaging portions of the eye in retaining contactwith the retention member(s), as at 340, as shown in FIG. 8. Further,depending on the particular construction of the retention member(s), theeye may be engaged in different ways. For example, in one embodiment,securing the corneal implant occurs by pressing the retention member(s)into the posterior cornea, as at 342, so as to removably retain thecorneal implant in position in relation thereto. In such an embodimentthe retention member(s) 24 is structured so as to hook, grasp, latchonto, or otherwise engage a portion of the eye, such as the posteriorcornea as shown in FIG. 3, in order to be retained thereby, while alsoallowing for removal of the corneal implant if necessary merely bydisengaging the retention members 24 from within the eye.

When a corneal implant 20 includes at least one haptic leg 28′, asdescribed, the method of inserting the corneal implant, as at 300, caninclude positioning the distal end of the haptic leg(s) 28′ incontacting relation to the iris and in biasing relation to the centralregion of the corneal implant against the posterior cornea, as at 332,and as shown in FIG. 8. In other cases, the distal end of the hapticleg(s) may be positioned in contacting relation to the iridocornealangle, as at 334. Furthermore, in some embodiments the placement andbiasing configuration of the haptic leg(s) may be sufficient to maintainpositioning of the corneal implant against the posterior cornea withonly contacting engagement of the distal end of the haptic leg(s) withthe iris and/or iridocorneal angle. In other embodiments, however, itmay be beneficial or desirable to secure the haptic leg(s) to the irisand/or iridocorneal angle, respectively, such as by penetration or otherfastening or to include additional retention members to engage the eye,to maintain stable positioning of the central region of the cornealimplant against the posterior cornea. Accordingly, the method mayfurther comprise securing the corneal implant to the posterior cornea byremovably pressing the distal end of the haptic leg into the iris, as at344, or into the iridocorneal angle, as at 346, depending on where thehaptic leg(s) is positioned to contact.

Finally, upon achieving proper positioning of the corneal implant, themethod as at 300 comprises closing the incision in the cornea. Forexample, closing the incision may occur by replacing a flap created bythe incision or delamination to its original location, whereupon theincision will close by the natural healing process of the eye.

In a further embodiment of the present method of inserting a cornealimplant of the present invention, as at 200, the corneal implant isinserted into the corneal stroma of the eye, and may be secured within apocket created in the cornea. This embodiment of the present method, asat 200, provides the benefit of being able to insert a corneal implantinto the corneal stroma while avoiding entering the anterior chamber ofthe eye, and thus avoiding potential endoocular infections, such asendophalmitis, that can result. Moreover, this method, as at 200, is asimple surgical procedure that any ophthalmic surgeon can perform.

As seen in FIG. 9, the method as at 200 comprises creating an incisionin the cornea of the eye, as at 210, although the incision may be madein other parts of the eye in proximity to the cornea, such as thesclera, so as to expose at least a portion of the corneal stroma.Preferably, the incision is made in the superficial layer of cornea,such as the surface, and as before, the incision can be a small incisionin the range of about 1.8 to 3.0 millimeters for inserting foldablecorneal implants, or can be larger such as approximately 6 millimetersto accommodate rigid corneal implants. Accordingly, the incision may beused to delaminate a plane of the cornea in a particular location toenable access to the corneal stroma. In some examples, the incision maybe configured to create a flap of tissue in which at least one portionis disconnected from the surrounding tissue but another side remainsintact. The flap may be pulled to one side, such as moving the detachededge about the retained edge, and held in such orientation for theremainder of the implant insertion process. Moreover, the incision canbe created manually (such as with a blade or razor), mechanically (suchas with a microkeratome or other device), or laser-assisted (such aswith a femtosecond laser).

The embodiment of the present method, as at 200, may further compriseexcising a portion of cornea from the eye through the incision, therebycreating a corneal pocket, as at 220. The amount, dimension, shape, andlocation of cornea excised or removed from the eye may vary depending onthe size of the corneal implant or as determined to be appropriate by asurgeon, ophthalmologist, or corneal specialist. For example, excising aportion of cornea may entail excising a portion of deep cornea, therebycreating a deep corneal stromal pocket, and may be excised from the sideof the cornea, as shown in FIG. 10 by the pocket 10′. Moreover, excisioncomprises removing a portion of corneal stroma that is at least as largein size and configuration as the corneal implant intended forimplantation. In some embodiments, the pocket is larger than the cornealimplant to enable the implant to be fully enclosed in the resultingpocket upon implantation. In other examples, the pocket may be smallerthan the full size of the corneal implant, but is sufficiently sized andlocated to permit access to the corneal stroma, whereby the cornealimplant extends from the pocket into the neighboring corneal stroma,such as is depicted in FIG. 10.

With reference to FIG. 9, the method as at 200 further comprisesinserting the corneal implant into the corneal stroma, as at 230. Thismay be accomplished through the incision, and when a corneal pocket ismade, through the corneal pocket. It should be understood, however, thatthe creation of and insertion through a corneal pocket is not requiredfor this embodiment of the method 200, and in some cases an incision isall that is necessary to access the corneal stroma. For example, if thecorneal implant is very thin, such as having a thickness ranging fromabout 10 micrometers to 125 micrometers, the corneal implant may beinserted directly into the corneal stroma without prior tissue excision.Indeed, the incision in the cornea creates access to the corneal stroma,into which the implant may be inserted, even in the absence of tissueexcision.

The corneal implant inserted by method 200 can be any implant, naturalor synthetic as described previously, but is preferably made of cleartransparent biocompatible material of medical grade quality, andpreferably does not contain any form of retention member(s), although insome embodiments retention members can be present for added securingupon placement. The implant may also preferably be made of semi-rigidyet foldable material. Accordingly, insertion of the implant may includecompressing the corneal implant to a dimension smaller than the size ofthe incision in the cornea as previously recited, and the opening of thecorneal pocket in cases where a pocket is created, for insertiontherethrough. Once inside the corneal stroma or pocket, compression onthe corneal implant is released, permitting the implant to assume itsnatural configuration within the stroma or pocket. However, it is alsocontemplated that corneal implant may not be foldable, and therefore issimply inserted through a larger incision and into the corneal pocket inits native configuration.

Once inserted into the corneal stroma, the method, as at 200, furthercomprises positioning the corneal implant within the stroma in engagingand fluid-flow limiting relation to the posterior cornea, as at 240. Asdescribed previously, the corneal implant is positioned so as to limitflow of anterior fluid into the cornea through the posteriorendothelium, such as to dehydrate the cornea from an edematous state toa normal level, and to maintain a normal level of corneal fluid onceobtained by preventing further excess anterior fluid from entering thecornea. In one example, proper positioning of the corneal implantincludes positioning the corneal implant within the corneal stromaadjacent to and anterior of the Descemet's membrane, as at 242. Forinstance, the corneal implant may be inserted through the corneal pocketand into the corneal stroma to be positioned adjacent to the Descemet'smembrane. Of course, it should be appreciated that positioning thecorneal implant, as at 240, may entail positioning the corneal implantanywhere in the corneal pocket and/or cornea that will limit the flow offluid into the cornea, such as by the posterior cornea.

FIGS. 10 and 11 illustrate examples of proper positioning of the cornealimplant 22 in relation to the cornea 10 as inserted in accordance withmethod 200. For example, FIG. 10 shows the corneal implant 20 positionedwithin the posterior cornea 12, having been inserted through a cornealpocket 10′, thus avoiding entering the anterior chamber 13. FIG. 11shows a cross-section of the cornea depicting one preferred placementfor the corneal implant 20 within the layers of the cornea 10. Forinstance, the corneal implant 20 is positioned near the posterior 12side of the cornea, just anterior to the natural Descemet's membrane 8.The corneal epithelium 5, anterior elastic lamina 6, stroma 7, andendothelium 9 are also shown for illustrative purposes.

In a preferred embodiment, the proper positioning of the corneal implantis maintained by virtue of the fit of the corneal implant within thecorneal pocket and/or corneal stroma, which is sufficiently tight tokeep the corneal implant from moving out of place, particularly when thecorneal implant is inserted or ‘wedged’ into the corneal stroma withoutthe use of a corneal pocket. However, additional structure may beincluded on the corneal implant, such as in the form of retentionmembers, to provide attachment points to retain the corneal implant inplace for additional securement of the corneal implant in position.

Finally, upon achieving proper positioning of the corneal implant, themethod as at 200 also comprises closing the incision in the cornea, asat 250, and as shown in FIG. 9. For example, as noted, closing theincision may occur by replacing a flap created by the incision ordelamination to its original location, whereupon the incision will closeby the natural healing process of the eye.

Looking now at yet another embodiment of the present method, as at 100,diagrammed in FIG. 12, once the corneal implant is inserted through theincisions and properly positioned relative to the posterior cornea, itis preferably bonded to the eye, such as using a laser. In particular, alaser is applied at a plurality of locations along a perimeter of thecorneal implant, as at 140, after it has been positioned within the eye.Specifically, the present invention contemplates the use of any laserthat provides matching or corresponding energy to the particularchromophore used to accomplish the laser bonding of the corneal implantto the posterior cornea. Naturally, the type of laser employed willutilize specific wavelengths of light and provide different amounts ofpower or thermal energy as compared with other lasers, the objectivepreferably being to utilize a laser that can achieve effective bondingas will be described, with minimal impact on the eye and the patent. Forexample, the laser may be a solid state laser, such as a neodymium-dopedyttrium aluminum garnet crystal (Nd:YAG) or ruby. Alternately, however,the laser may be a gas laser, such as comprising helium (He), nitrogen(N), argon (Ar), or carbon dioxide (CO₂) as the lasing medium. Infurther examples, the laser may be a fiber optic, or preferably, a diodeor diode-pumped laser, and may be ultrafast, such as a femtosecondlaser.

In particular, the step of applying the laser, as at 140, entailsdirecting the laser to a desired focal point where the energy of thelaser is concentrated. The focal point of the laser can include at thesurface of the corneal implant, at a point within the posterior cornea,at the junction of the corneal implant with the posterior surface of thecornea, and/or at some other location sufficient to achieve excitationand an increase in thermal energy in the corneal implant as well as thecorresponding posterior cornea. Moreover, the laser can be operated toprovide continuous laser light, and therefore continuous energy, or canbe applied in pulses or short bursts, such as to minimize trauma to theeye.

In this embodiment of the present method, as at 100, once applied, thelaser application is maintained until the implant is bonded to theposterior cornea of the patient, as at 150. In this regard, the laser ispreferably maintained at each location along a perimeter of the cornealimplant where attachment is desired so as to bond the implant to theposterior cornea at that particular location. Bonding generally occurswhen the light energy provided by the laser is converted to thermalenergy and the corneal implant and abutting posterior cornea are heateduntil they coalesce, that is, until the corresponding portions of theimplant and posterior cornea subject to the laser application melttogether. Cessation of the laser application then initiates cooling ofthe melted portion, after which the corneal implant and posterior corneaare securely joined at that location.

Applying 140 and maintaining 150 the laser is performed until aplurality of locations of the corneal implant are bonded to theposterior cornea. This can occur at successive distinct locations alongthe corneal implant, moving to a new location once a previous locationis securely bonded, although it is noted that continuous movement aboutthe perimeter of the corneal implant so as to achieve complete securingabout the perimeter such that uninterrupted lengths of the cornealimplant are bonded to the posterior cornea, or to achieve larger thanmerely spot attachment points is also contemplated. Moreover, the numberof locations of laser application and bonding may vary so long as thereare at least a sufficient number of locations to secure the cornealimplant to the posterior cornea in a particular position relativethereto. For instance, in some embodiments, a minimum of two or threeproperly spaced bonding locations is all that may be needed to securethe corneal implant in place. As noted, in some embodiments, however,the laser is applied and maintained along substantially the entireperimeter of the corneal implant, such that multiple points along theentire circumference of the corneal implant are bonded to the posteriorcornea, however, this may be less preferred if some ‘breathability’ isdesired. The length of such laser application may vary based on what isdetermined by the surgeon, corneal or other ophthalmologic professionalperforming the present method deems appropriate and/or necessary. Forexample, the laser can be applied and maintained to create essentially adashed line along the perimeter of the corneal implant which bonds theimplant to the posterior cornea. Of course, in all embodiments, thenumber of points will depend on the size and circumference of thecorneal implant, as well as on the size of the focal point of the laser,the thermal energy created by the laser, and the size of resultingmelted material that subsequently cools together. As with the otherembodiments, once the corneal implant is effectively positioned andsecured, the incisions may be closed or be permitted to close vianatural healing.

Since many modifications, variations and changes in detail can be madeto the described preferred embodiment of the invention, it is intendedthat all matters in the foregoing description and shown in theaccompanying drawings be interpreted as illustrative and not in alimiting sense. Thus, the scope of the invention should be determined bythe appended claims and their legal equivalents.

Now that the invention has been described,

1. A method of inserting a corneal implant comprising: creating anincision in the eye in proximity to a cornea, inserting a cornealimplant which comprises a central region and at least one retentionmember extending from a periphery of the central region through theincision, positioning the corneal implant in engaging and fluid-flowlimiting relation to the posterior cornea; and securing the cornealimplant in said engaging and fluid-flow limiting relation to theposterior cornea by engaging portions of the eye in retaining contactwith the at least one retention member of the corneal implant.
 2. Themethod as recited in claim 1 wherein securing the corneal implantfurther comprises pressing the at least one retention member into theposterior cornea so as to removably retain the corneal implant inposition in relation thereto.
 3. The method as recited in claim 1wherein inserting the corneal implant further comprises compressing thecorneal implant to a dimension smaller than the incision for insertiontherethrough.
 4. The method as recited in claim 1 wherein inserting thecorneal implant having a central region and at least one retentionmember further comprises inserting the corneal implant having thecentral region and at least one haptic leg secured to and extending fromthe central region of the corneal implant.
 5. The method as recited inclaim 4 wherein securing the corneal implant further comprisespositioning a distal end of the at least one haptic leg in contactingrelation to the iris and in biasing relation to the central region ofthe corneal implant against the posterior of the cornea.
 6. The methodas recited in claim 5 wherein securing the corneal implant furthercomprises removably pressing the distal end of the at least one hapticleg into the iris.
 7. The method as recited in claim 4 whereinpositioning the corneal implant further comprises positioning a distalend of the at least one haptic leg in contacting relation to theiridocorneal angle and in biasing relation to the central region of thecorneal implant against the posterior of the cornea.
 8. The method asrecited in claim 7 wherein securing the corneal implant furthercomprises removably pressing the distal end of the at least one hapticleg into the iridocorneal angle.
 9. A corneal implant comprising: acentral region made of a biocompatible polymer material and configuredto correspond to a contour of a posterior cornea, at least one retentionmember secured to and extending away from a periphery of said centralregion of said corneal implant and structured to removably retain saidcorneal implant in position in relation to the posterior cornea uponimplantation, and said at least one retention member including a contactpoint disposed distally from said central region of said corneal implantand in contacting relation with an eye of a patient, upon implantation,said contact point structured to retain of said corneal implant inabutting engagement with the posterior cornea.
 10. The corneal implantas recited in claim 9 wherein said central region comprises an arcuateconfiguration.
 11. The corneal implant as recited in claim 10 whereinsaid central region comprises an anterior curvature structured tocorrespondingly match a curvature of the posterior cornea.
 12. Thecorneal implant as recited in claim 9 wherein said central regioncomprises a vision correcting configuration.
 13. The corneal implant asrecited in claim 9 wherein said central region comprises a hydrophobicmaterial.
 14. The corneal implant as recited in claim 9 wherein saidcentral region is structured to inhibit the flow of excess cornealfluid.
 15. The corneal implant as recited in claim 9 wherein saidcorneal implant is structured to be at least temporarily foldable so asto reduce a dimension thereof for implantation.
 16. The corneal implantas recited in claim 9 wherein said retention member comprises at leastone haptic leg secured to and extending away from said central regionand including said contact point disposed distally from said centralregion, said haptic leg including a biased configuration structured tobias said central region against the posterior cornea.
 17. The cornealimplant as recited in claim 16 wherein said contact point of said atleast one haptic leg is structured and disposed releaseably engage aportion of an iris.
 18. The corneal implant as recited in claim 16wherein said contact point of said at least one haptic leg is structuredand disposed to releaseably engage a portion of an iridocorneal angle.19. The corneal implant as recited in claim 16 wherein said at least onehaptic leg is configured to exert pressure on said central regionagainst the posterior cornea so as to maintain positioning of saidcentral region upon implantation.
 20. A method of inserting a cornealimplant comprising: creating an incision in the eye in proximity to thecornea which exposes at least a portion of the corneal stroma, insertinga corneal implant through the incision and into the corneal stroma,positioning the corneal implant in engaging and fluid-flow limitingrelation to the posterior cornea to treat corneal edema, and closing theincision.
 21. The method as recited in claim 20 further comprisingpositioning the corneal implant in adjacent relation and anterior to theDescemet's membrane.
 22. The method as recited in claim 20 furthercomprising excising a portion of corneal stroma, thereby creating acorneal pocket.
 23. The method as recited in claim 22 wherein insertingthe corneal implant comprises inserting the corneal implant through theincision and through corneal pocket into the corneal stroma.
 24. Themethod as recited in claim 20 wherein inserting a corneal implantfurther comprises compressing the corneal implant to a dimension smallerthan the size of the incision for insertion therethrough.
 25. The methodas recited in claim 20 wherein inserting a corneal implant comprisesinserting a corneal implant having a vision correcting configuration.26. A method of inserting a corneal implant comprising: creating anincision in the eye in proximity to the cornea, inserting the cornealimplant into the cornea through the incision, positioning the cornealimplant in engaging and fluid-flow limiting relation to the posteriorcornea, applying a laser at a plurality of locations along a perimeterof the corneal implant, and maintaining the laser application until thecorneal implant is bonded to the posterior cornea at least at theplurality of locations along the perimeter of the corneal implant. 27.The method as recited in claim 1 wherein inserting a corneal implantfurther comprises compressing the corneal implant to a dimension smallerthan the size of the incision for insertion therethrough.
 28. The methodas recited in claim 26 wherein applying the laser further comprisesapplying the laser along substantially the entire perimeter of thecorneal implant.
 29. The method as recited in claim 26 wherein applyingthe laser further comprises applying the laser continuously along theperimeter of the corneal implant.
 30. The method as recited in claim 26wherein inserting the corneal implant further comprises inserting acorneal implant formed of a biocompatible polymer material.
 31. Themethod as recited in claim 26 wherein inserting the corneal implantfurther comprises inserting a corneal implant formed of a hydrophobicmaterial.
 32. The method as recited in claim 26 wherein inserting thecorneal implant comprises inserting a corneal implant having a visioncorrecting configuration and positioning the corneal implant in visioncorrecting relation to the posterior cornea.
 33. The method as recitedin claim 26 wherein positioning the corneal implant further comprisespositioning the corneal implant in the posterior cornea to treat excesscorneal fluid.